Safety paper



Patented Aug. 4, 1931 UNITED STATES PATENT OFFICE.

BURGESS W. SMITH, OF ROCHESTER, NEW YORK, ASSIGNOR TO THE TODD COMPANY, INC., OF ROCHES'IER, NEW YORK, A CORPORATION OF NEW YORK SAFETY PAPER Application filed February 20, 1924. Serial No. 694,040.

This invention relates to safety paper for :hecks, drafts, bonds, and other commercial oaper instruments, having as its chief object zhe provision of an advantageous paper of ;his character of a comparatively simple na- ;ure economical to produce and applicable to t Wide range of conditions and requirements. l Iore specifically stated, it is an object of the )resent invention'to provide a paper of the tbove character having an inherently warnng character applied thereto in an initially nvisible manner but adapted to be rendered :onspicuous by reaction with eradicating lgGIltS, such as the bleaching fluids in common use for making erasures, to thereby afford, for example, a white or plain paper, or

me having any preferred pattern or other mpression on it.

To these and other ends the invention re ides in certain Improvements and comb1naions of parts all as will be hereinafter more ?ully described, the novel features being Jointed out in the claims at the end of the pecification.

In the drawings:

Fig. 1 shows a check made of safety paper raving the present invention applied thereto nd illustrating the results of an attempted hemical erasure.

Fig. 2 is"v an enlarged fragmentary view of he portion of Fig. 1 illustrating the attemptd erasure.

Fig. 3 is an enlarged sectional view of the a er.

Fig. 4 is a view similar to Fig. 2 but show,- ng a modified form of application, and i Fig. 5 is a sectional view similar to Figure but illustrating the modification of Fig. 4.

Similar reference numerals throughout the everal views indicate the same parts.

The present invention is in the nature of n improvement upon the inventionsfdislosed in my Letters Patent No. 1,454,837

lated May 8, 1923, for' Safety paper and iethod of making same, and in my Letters *atent No. 1,675,769, dated July 3, 1928,for

rotective papers and methods of making ame, which relate to the use of a warning haracter for the paper, camouflaged and hus rendered inconspicuous by an additional suitable impression. The present invention on the other hand affords a safety paper provided with Warning means requiring no camouflaging or additional concealing matter and is therefore adapted for the production of safety paper having a white or plain surface, or one marked with a particular pattern or other impression not adapted to serve as camouflaging. This invention comprises, more specifically, the printing of the warning means in an invisible manner, and with indelible and initially invisible ink, adapted to react with and to be rendered conspicuously visible by eradicating reagents applied to the paper for making an erasure.

The warning means may take the form of any suitable character or symbol provided it is of such a nature as to be generally recognized as expressing a warning meaning. While various marks, signs and words are available for this purpose, it is preferred to use the word, Void, because of its generally recognized significance, and this word is preferably-printed in repetition over the entire paper 10, as indicated in the drawings, or at least over such portions of a check or other instruments made therefrom as it is particularly desirable to protect.

Preferably also, the word is printed in relathe effect of the ink on the light reflecting action of the paper. This may be accomplished to a degree b the use of finelines employed, for examp e, for printing merely the outlines of a character or the letters of a word. It is preferred, however, to accomplis'h this result by breaking up the continulty of the lines such as form the letters of the word, into. a multiplicity of substantially isolated'areas, spots or dots. Such areas arepreferably formed as circular dots,-

as shown at 11, Figure 2,. which have been found to lend themselves advantageously to 'the desired result of reducing visibility of having a slightly rough surface, such as it is preferred to use.

The desired results may be obtained by the use of various inks having the desired initial invisibility, combined with the qualities of indelibility and of sensitiveness under the action of ink eradicating chemicals. It is preferred to employ an ink of an initially colorless character such, for example, as one containing manganese ferrocyanide, tolidine hydrochloride, or benzidine sulphate, used as a medium with oil Varnish, or with a water varnish having for its base glycerine and gum arabie. To this may be added a small quantity of oxide of zinc, or zinc white, since these organic substances, in common with other organic compounds, are affected by the action of light corresponding to the lower invisible part of the spectrum which part is almost totally absorbed by the zinc white which thus serves as an effective protective medium against this influence for rendering the ink stable. These substances react cffectively with ink eradicating chemicals generally such, for example, as bleaching reagents, and develop conspicuous colors of an indelible character so that characters printed therewith are thus rendered conspicuously visible.

As a further means for insuring invisibility of the impression as initially printed, use is made of the fact that characters printed in a negative form of impression are less visible than when printed positively, because of the trained aptitude of the normal eye for seeing positive impressions. That is to say, instead of printing the line sections or dots on a blank or unprinted background, it has been found advantageous to form these elements as unprinted surface portions 11, on a printed ground 12, Figure 2, where the lining is intended to denote color, and the circles about the dots 11 are conventional merely. The result is that the major portion of the paper surface has the ink applied thereto. and such differences as exist in the light reflecting actions of unprinted and printed surfaces, render the latter the darker of the two, so that the characters themselves have a reversedor negative form of impression less easily discerned by the eye than ifdarker than the background. This negative form of impression has the further-advantage of producing the development of indelible color over a major portion of the surface to which an eradicator is applied, so that a striking result is obtained.

An impression of the warning matter as above described may be made on plain paper and be invisible in any light at any angle of reflection and thus provides an effectively protected paper which may be very light in tint or even white, as frequently preferred byreason, for-example, of the distinct legibility which is afforded for matter written paper having an additional impression of av simple, arbitrary lined pattern 15 as shown. The latter is preferably printed with fugitive ink removed by the eradicator as indicated at the locality of application thereof, 16. The use ofsuch a pattern, especially if printed lightly on the surface of the paper, serves as a protection against erasure by abrasive treatment, since it is removed at the locality of such treatment leaving a surface contrasting with adjaccnt portions to warn of alteration. The paper employed may furthermore be of the known variety containing a chemical adapted to develop a stain or color contrast at portions 'to which chemical eradicators are applied, as well understood in the art, to increase the conspicuousness with which alterations are shown, as an additional protective step. The invention is thus applicable to paper having any color or pattern and provides a safety paper all portions of which are protected by an indelible and effective warning character which may be economically applied by a single printing impression.

I claim as my invention:

lpA safety paper having an inherently warning character formed thereon as an unprinted surface portion on a ground printed in ink of an indelible and initially invisible character adapted to react with and to be rendered conspicuously-Visible by eradicating fluids applied to the paper.

2. A safety paper having an inherently warning character repeatedly marked thereon by lines broken up into substantially isolated areas formed as unprinted surface portions on a ground printed in ink of an in delible and initially invisible character adapted to react with and to be rendered conspicuousl visible by eradicating fluids applied to tiie paper.

3. A safety paper having a word expressing a warning repeatedly marked thereon in staggered arrangement with the lines of the letters of said word broken up into substantially isolated and commingled areas formed as unprinted surface portions on a ground printed in indelible and initially colorless ink adapted to be acted upon and rendered conspicuously visible by an eradicating fluid applied to the paper for'making an erasure.

4. A safety paper comprising a background formed by ink of an initially substantially invisible but sensitive character, said ground surrounding inherently warning indicia and being adapted to react with and to be conspicuously altered in color by an ink eradicating fluid, relative to said warnin'g indicia, to indicate an attempted erasure.

5. A safety paper comprising a background formed by ink of an initially substantially invisible but sensitive and indelible character, said ground surrounding inherently warning indicia repeated thereover and being adapted to react with an eradicating fluid to produce a color for said background diiferent from that of said indicia, to render said indicia visible and to conspicuously stain said paper over a major portion of the area affected by said eradicating fluid.

6. The 'method of making safety paper which consists in applying to the paper a colorless chemical solution, which is visibly reactive to eradicating agents, in such manner as to form a background for warning indicia appearing in reverse print against said background, which indicia when the background is rendered visible would inherently nullify the paper.

7. A safety paper carrying indicia thereon in reverse print against a background of a normally invisible chemical compound which is visibly reactive to eradicating agents, the indicia comprising a word or words which, when read against the visible background would inherently nullify the paper.

8. A safety paper carrying warning indicia thereon in reverse print against an impressed background of a normally colorless chemical compound which is visibly reactive to eradicating agents.

BURGESS W. SMITH. 

